Not sure if this is a homing/calibration problem?

I ran in to a sudden problem with my x-carve, and I’m not sure if it’s homing, calibration, or zeroing, that’s causing the problems. It also doesn’t help that I don’t claim to know the difference between all the terms! :grinning:

So, I always start my carving from the top right corner of the stock (toolpath using Meshcam, output via UGS). But the last couple of carves something has gone wrong either in x-carve or my software where the Y axis is consistently off by about 10 mm towards the front of the machine. I was able to stop, restart, and complete those carves by changing my starting position to compensate for the extra 10 mm on the Y axis, but this is clearly not a long term fix.

I’m sure this is a basic sort of problem, but since I’m uncertain of my terminology I’m not exactly sure where to look for help. I know Easel has a “homing” process that I’ve done a couple of times before, but does that really do anything for my machine afterwards once I close down Easel and go back to UGS? I avoid using Easel like the plague because 8 times out of 10 it refuses to “see” the x-carve, whereas I never have that problem with UGS.

Homing is a process that occurs in the grbl code that resides on the Arduino. Programs like Easel and most G-code senders will have a command that you can use to tell grbl to home the machine (UGCS uses $H as the homing command).

Once the machine is homed then you can move around among the programs that send G-code and Machine zero is still valid unless you perform a command/function to change it or remove power from the Arduino.

There are lots of things that can cause position errors. Start by reading this:

Thanks for the advice, Larry. Read that link, and I definitely don’t think there are mechanical issues. All belts and v-wheels are snug, nothing is binding. I completely forgot about the $H command in UGCS. Is the basic usage of $H such that I place my bit on the surface of the top right corner (as I’ve set for a starting position in Meshcam), then enter $H at the command line of UGCS?

No. Homing ($H) is not setting the position of Work Zero. Homing will move the Z axis up until it trips the homing switch, then it will start moving X and Y at the same time until they trip the X and Y homing switch, respectively.

This sets your Machine Zero position.

Then you would jog your machine to the location that you want the carve to start (in your case the top right corner) with the bit just barely above the work surface (the width of a piece of paper). Then you would press the “Reset Zero” button in UGCS which would set your Work Zero position.

Then you are ready to start your carve.

That’s perfect, Larry. Thanks for the help!